1. Field of the Invention
The present invention relates to an oil supply structure of a water-cooled internal combustion engine to be mounted on a vehicle.
2. Description of Background Art
A water-cooled internal combustion engine is known that includes a water pump operatively connected to a cooling system and an oil pump operatively connected to a lubrication system being provided on both sides of a balancer shaft that is placed parallel with a crankshaft. An oil pump drive shaft and a water pump drive shaft are coaxially coupled with both ends of the balancer shaft so that the water pump and the oil pump are driven with a simplest structure with a small number of parts. See, for example, JP-A No. 2008-64079.
The water-cooled internal combustion engine disclosed in JP-A No. 2008-64079 is mounted in a vehicle in a so-called vertical placement posture in which the crankshaft is oriented in the vehicle body front-rear direction, the water pump drive shaft of the water pump is coaxially coupled with the front end of the balancer shaft placed parallel with the crankshaft, and the oil pump drive shaft of the oil pump is coaxially coupled with the rear end of the balancer shaft.
The water-cooled internal combustion engine comprises a water-cooled oil cooler with the oil cooler being placed further forward than a radiator of the cooling system placed at a front part of a vehicle body.
Because water piping of the cooling system that couples the water pump is provided at a front part of the internal combustion engine, the radiator placed at a front part of the vehicle body, or the like is structured at a front area of the vehicle body. The water piping may extend a little and coupled with the oil cooler so that oil flowing thorough the oil cooler can be easily cooled.